diff --git a/core/api/src/main/java/org/onosproject/cluster/LeadershipEvent.java b/core/api/src/main/java/org/onosproject/cluster/LeadershipEvent.java
index faf6dd4..d1fe670 100644
--- a/core/api/src/main/java/org/onosproject/cluster/LeadershipEvent.java
+++ b/core/api/src/main/java/org/onosproject/cluster/LeadershipEvent.java
@@ -31,20 +31,23 @@
      */
     public enum Type {
         /**
-         * Signifies that the leader has been elected. The event subject is the
-         * new leader.
+         * Signifies that the leader has been elected.
+         * The event subject is the new leader.
+         * This event does not guarantee accurate candidate information.
          */
         LEADER_ELECTED,
 
         /**
-         * Signifies that the leader has been re-elected. The event subject is the
-         * leader.
+         * Signifies that the leader has been re-elected.
+         * The event subject is the leader.
+         * This event does not guarantee accurate candidate information.
          */
         LEADER_REELECTED,
 
         /**
-         * Signifies that the leader has been booted and lost leadership. The
-         * event subject is the former leader.
+         * Signifies that the leader has been booted and lost leadership.
+         * The event subject is the former leader.
+         * This event does not guarantee accurate candidate information.
          */
         LEADER_BOOTED,
 
diff --git a/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java b/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
index 03281be..4ee9a00 100644
--- a/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
+++ b/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
@@ -491,9 +491,12 @@
                 if (Objects.equals(requested, mastershipService.getLocalRole(deviceId))) {
                     return;
                 } else {
-                    return;
-                    // FIXME roleManager got the device to comply, but doesn't agree with
+                    log.warn("Role mismatch on {}. set to {}, but store demands {}",
+                             deviceId, response, mastershipService.getLocalRole(deviceId));
+                    // roleManager got the device to comply, but doesn't agree with
                     // the store; use the store's view, then try to reassert.
+                    backgroundService.submit(() -> reassertRole(deviceId, mastershipService.getLocalRole(deviceId)));
+                    return;
                 }
             } else {
                 // we didn't get back what we asked for. Reelect someone else.
@@ -547,6 +550,7 @@
         provider.roleChanged(deviceId, newRole);
 
         if (newRole.equals(MastershipRole.MASTER)) {
+            log.debug("sent TriggerProbe({})", deviceId);
             // only trigger event when request was sent to provider
             provider.triggerProbe(deviceId);
         }
@@ -565,12 +569,19 @@
 
         MastershipRole myNextRole = nextRole;
         if (myNextRole == NONE) {
-            mastershipService.requestRoleFor(did);
-            MastershipTerm term = termService.getMastershipTerm(did);
-            if (term != null && localNodeId.equals(term.master())) {
-                myNextRole = MASTER;
-            } else {
-                myNextRole = STANDBY;
+            try {
+                mastershipService.requestRoleFor(did).get();
+                MastershipTerm term = termService.getMastershipTerm(did);
+                if (term != null && localNodeId.equals(term.master())) {
+                    myNextRole = MASTER;
+                } else {
+                    myNextRole = STANDBY;
+                }
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                log.error("Interrupted waiting for Mastership", e);
+            } catch (ExecutionException e) {
+                log.error("Encountered an error waiting for Mastership", e);
             }
         }
 
diff --git a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
index 3bb6a70..b2ee832 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
@@ -15,6 +15,7 @@
  */
 package org.onosproject.store.cluster.impl;
 
+import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
 
@@ -163,7 +164,7 @@
     @Override
     public State getState(NodeId nodeId) {
         checkNotNull(nodeId, INSTANCE_ID_NULL);
-        return nodeStates.get(nodeId);
+        return MoreObjects.firstNonNull(nodeStates.get(nodeId), State.INACTIVE);
     }
 
     @Override
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DistributedLeadershipManager.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DistributedLeadershipManager.java
index 1882b1b..704df83 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DistributedLeadershipManager.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DistributedLeadershipManager.java
@@ -96,17 +96,26 @@
     protected EventDeliveryService eventDispatcher;
 
     private final Logger log = getLogger(getClass());
+
     private ScheduledExecutorService electionRunner;
     private ScheduledExecutorService lockExecutor;
     private ScheduledExecutorService staleLeadershipPurgeExecutor;
     private ScheduledExecutorService leadershipRefresher;
 
+    // leader for each topic
     private ConsistentMap<String, NodeId> leaderMap;
+    // list of candidates (includes chosen leader) for each topic
     private ConsistentMap<String, List<NodeId>> candidateMap;
 
     private ListenerRegistry<LeadershipEvent, LeadershipEventListener> listenerRegistry;
+
+    // cached copy of leaderMap
+    // Note: Map value, Leadership, does not contain proper candidates info
     private final Map<String, Leadership> leaderBoard = Maps.newConcurrentMap();
+    // cached copy of candidateMap
+    // Note: Map value, Leadership, does not contain proper leader info
     private final Map<String, Leadership> candidateBoard = Maps.newConcurrentMap();
+
     private final ClusterEventListener clusterEventListener = new InternalClusterEventListener();
 
     private NodeId localNodeId;
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/ECDeviceStore.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/ECDeviceStore.java
index 2dae55b..2631fff 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/device/impl/ECDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/ECDeviceStore.java
@@ -286,6 +286,11 @@
             deviceDescriptions.put(new DeviceKey(providerId, deviceId), deviceDescription);
             return refreshDeviceCache(providerId, deviceId);
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
             DeviceInjectedEvent deviceInjectedEvent = new DeviceInjectedEvent(providerId, deviceId, deviceDescription);
             return Futures.getUnchecked(
                     clusterCommunicator.sendAndReceive(deviceInjectedEvent,
@@ -413,6 +418,11 @@
             });
             deviceEvents = refreshDevicePortCache(providerId, deviceId, Optional.empty());
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
             if (master == null) {
                 return Collections.emptyList();
             }
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
index a9a9098..03e28f1 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
@@ -330,6 +330,11 @@
             }
 
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
             // FIXME Temporary hack for NPE (ONOS-1171).
             // Proper fix is to implement forwarding to master on ConfigProvider
             // redo ONOS-490
@@ -579,6 +584,11 @@
             }
 
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
             // FIXME Temporary hack for NPE (ONOS-1171).
             // Proper fix is to implement forwarding to master on ConfigProvider
             // redo ONOS-490
diff --git a/core/store/dist/src/main/java/org/onosproject/store/link/impl/ECLinkStore.java b/core/store/dist/src/main/java/org/onosproject/store/link/impl/ECLinkStore.java
index 243caf8..3d3ff9a 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/link/impl/ECLinkStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/link/impl/ECLinkStore.java
@@ -218,6 +218,13 @@
             linkDescriptions.compute(internalLinkKey, (k, v) -> createOrUpdateLinkInternal(v  , linkDescription));
             return refreshLinkCache(linkKey);
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
+            // Temporary hack for NPE (ONOS-1171).
+            // Proper fix is to implement forwarding to master on ConfigProvider
             if (dstNodeId == null) {
                 return null;
             }
diff --git a/core/store/dist/src/main/java/org/onosproject/store/link/impl/GossipLinkStore.java b/core/store/dist/src/main/java/org/onosproject/store/link/impl/GossipLinkStore.java
index 47aa85c..06402cf 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/link/impl/GossipLinkStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/link/impl/GossipLinkStore.java
@@ -323,6 +323,11 @@
             }
 
         } else {
+            // Only forward for ConfigProvider
+            // Forwarding was added as a workaround for ONOS-490
+            if (!providerId.equals("cfg")) {
+                return null;
+            }
             // FIXME Temporary hack for NPE (ONOS-1171).
             // Proper fix is to implement forwarding to master on ConfigProvider
             // redo ONOS-490
diff --git a/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java b/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
index c6fc693..44fbea0 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
@@ -159,20 +159,12 @@
         checkArgument(deviceId != null, DEVICE_ID_NULL);
 
         String leadershipTopic = createDeviceMastershipTopic(deviceId);
-        if (connectedDevices.add(deviceId)) {
-            return leadershipService.runForLeadership(leadershipTopic)
-                                    .thenApply(leadership -> {
-                                        return Objects.equal(localNodeId, leadership.leader())
-                                                ? MastershipRole.MASTER : MastershipRole.STANDBY;
-                                    });
-        } else {
-            NodeId leader = leadershipService.getLeader(leadershipTopic);
-            if (Objects.equal(localNodeId, leader)) {
-                return CompletableFuture.completedFuture(MastershipRole.MASTER);
-            } else {
-                return CompletableFuture.completedFuture(MastershipRole.STANDBY);
-            }
-        }
+        connectedDevices.add(deviceId);
+        return leadershipService.runForLeadership(leadershipTopic)
+                .thenApply(leadership -> {
+                    return Objects.equal(localNodeId, leadership.leader())
+                            ? MastershipRole.MASTER : MastershipRole.STANDBY;
+                });
     }
 
     @Override
diff --git a/protocols/openflow/api/src/main/java/org/onosproject/openflow/controller/driver/AbstractOpenFlowSwitch.java b/protocols/openflow/api/src/main/java/org/onosproject/openflow/controller/driver/AbstractOpenFlowSwitch.java
index 098ff07..a877a66 100644
--- a/protocols/openflow/api/src/main/java/org/onosproject/openflow/controller/driver/AbstractOpenFlowSwitch.java
+++ b/protocols/openflow/api/src/main/java/org/onosproject/openflow/controller/driver/AbstractOpenFlowSwitch.java
@@ -97,6 +97,9 @@
     protected ExecutorService executorMsgs =
             Executors.newFixedThreadPool(2, groupedThreads("onos/of", "ctrl-msg-stats-%d"));
 
+    // messagesPendingMastership is used as synchronization variable for
+    // all mastership related changes. In this block, mastership (including
+    // role update) will have either occurred or not.
     private final AtomicReference<List<OFMessage>> messagesPendingMastership
             = new AtomicReference<>();
 
@@ -275,6 +278,8 @@
     public final void handleMessage(OFMessage m) {
         if (this.role == RoleState.MASTER || m instanceof OFPortStatus) {
             this.agent.processMessage(dpid, m);
+        } else {
+            log.trace("Dropping received message {}, was not MASTER", m);
         }
     }
 
@@ -309,7 +314,8 @@
         synchronized (messagesPendingMastership) {
             List<OFMessage> messages = messagesPendingMastership.get();
             if (messages != null) {
-                this.sendMsg(messages);
+                // Cannot use sendMsg here. It will only append to pending list.
+                sendMsgsOnChannel(messages);
                 log.debug("Sending {} pending messages to switch {}",
                           messages.size(), dpid);
                 messagesPendingMastership.set(null);
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
index f9a6059..5bca54e 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
@@ -73,12 +73,12 @@
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
-
 import static org.onlab.util.Tools.groupedThreads;
 
 @Component(immediate = true)
@@ -118,11 +118,11 @@
     private final ExecutorService executorBarrier =
         Executors.newFixedThreadPool(4, groupedThreads("onos/of", "event-barrier-%d"));
 
-    protected ConcurrentHashMap<Dpid, OpenFlowSwitch> connectedSwitches =
+    protected ConcurrentMap<Dpid, OpenFlowSwitch> connectedSwitches =
             new ConcurrentHashMap<>();
-    protected ConcurrentHashMap<Dpid, OpenFlowSwitch> activeMasterSwitches =
+    protected ConcurrentMap<Dpid, OpenFlowSwitch> activeMasterSwitches =
             new ConcurrentHashMap<>();
-    protected ConcurrentHashMap<Dpid, OpenFlowSwitch> activeEqualSwitches =
+    protected ConcurrentMap<Dpid, OpenFlowSwitch> activeEqualSwitches =
             new ConcurrentHashMap<>();
 
     protected OpenFlowSwitchAgent agent = new OpenFlowSwitchAgent();
@@ -280,6 +280,7 @@
             executorMsgs.submit(new OFMessageHandler(dpid, msg));
             break;
         case ERROR:
+            log.debug("Received error message from {}: {}", dpid, msg);
             executorMsgs.submit(new OFMessageHandler(dpid, msg));
             break;
         case STATS_REPLY:
diff --git a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LldpLinkProvider.java b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LldpLinkProvider.java
index 981686b..9885521 100644
--- a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LldpLinkProvider.java
+++ b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LldpLinkProvider.java
@@ -64,6 +64,7 @@
 import org.onosproject.net.config.NetworkConfigListener;
 import org.onosproject.net.config.NetworkConfigRegistry;
 import org.onosproject.net.device.DeviceEvent;
+import org.onosproject.net.device.DeviceEvent.Type;
 import org.onosproject.net.device.DeviceListener;
 import org.onosproject.net.device.DeviceService;
 import org.onosproject.net.flow.DefaultTrafficSelector;
@@ -568,6 +569,9 @@
     private class InternalDeviceListener implements DeviceListener {
         @Override
         public void event(DeviceEvent event) {
+            if (event.type() == Type.PORT_STATS_UPDATED) {
+                return;
+            }
             Device device = event.subject();
             Port port = event.port();
             if (device == null) {
diff --git a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
index 0950166..a1386ae 100644
--- a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
+++ b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
@@ -268,7 +268,7 @@
                 LOG.error("Unknown Mastership state : {}", newRole);
 
         }
-        LOG.debug("Accepting mastership role change for device {}", deviceId);
+        LOG.debug("Accepting mastership role change to {} for device {}", newRole, deviceId);
     }
 
 
@@ -297,7 +297,7 @@
     }
 
     private void pushPortMetrics(Dpid dpid, List<OFPortStatsEntry> portStatsEntries) {
-        DeviceId deviceId = DeviceId.deviceId(dpid.uri(dpid));
+        DeviceId deviceId = DeviceId.deviceId(Dpid.uri(dpid));
         Collection<PortStatistics> stats = buildPortStatistics(deviceId, portStatsEntries);
         providerService.updatePortStatistics(deviceId, stats);
     }
@@ -434,6 +434,7 @@
 
         @Override
         public void switchChanged(Dpid dpid) {
+            LOG.debug("switchChanged({})", dpid);
             if (providerService == null) {
                 return;
             }
@@ -442,17 +443,21 @@
             if (sw == null) {
                 return;
             }
-            providerService.updatePorts(did, buildPortDescriptions(sw));
+            final List<PortDescription> ports = buildPortDescriptions(sw);
+            LOG.debug("switchChanged({}) {}", did, ports);
+            providerService.updatePorts(did, ports);
         }
 
         @Override
         public void portChanged(Dpid dpid, OFPortStatus status) {
+            LOG.debug("portChanged({},{})", dpid, status);
             PortDescription portDescription = buildPortDescription(status);
             providerService.portStatusChanged(deviceId(uri(dpid)), portDescription);
         }
 
         @Override
         public void receivedRoleReply(Dpid dpid, RoleState requested, RoleState response) {
+            LOG.debug("receivedRoleReply({},{},{})", dpid, requested, response);
             MastershipRole request = roleOf(requested);
             MastershipRole reply = roleOf(response);
             providerService.receivedRoleReply(deviceId(uri(dpid)), request, reply);
@@ -503,7 +508,7 @@
                     LOG.debug("Ports Of{}", portsOf);
                     portsOf.forEach(
                         op -> {
-                            portDescs.add(buildPortDescription(type, (OFObject) op));
+                            portDescs.add(buildPortDescription(type, op));
                         }
                      );
                     });
diff --git a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
index b87d37b..2801f12 100644
--- a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
+++ b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
@@ -353,10 +353,12 @@
                 return;
             }
             if (isGroupSupported(sw)) {
-                GroupStatsCollector gsc = new GroupStatsCollector(
-                        controller.getSwitch(dpid), POLL_INTERVAL);
+                GroupStatsCollector gsc = new GroupStatsCollector(sw, POLL_INTERVAL);
                 gsc.start();
-                collectors.put(dpid, gsc);
+                GroupStatsCollector prevGsc = collectors.put(dpid, gsc);
+                if (prevGsc != null) {
+                    prevGsc.stop();
+                }
             }
 
             //figure out race condition